There are substrate processing apparatuses known in the related art used to execute specific types of processing such as etching and film formation on a substrate to be processed (to be referred to simply as substrate subsequently), which may be a semiconductor wafer, a liquid crystal substrate or the like, placed on a stage disposed in a processing chamber by supplying a processing gas into the processing chamber. Such a substrate processing apparatus normally includes a gas supply system for supplying the processing gas into the processing chamber and an evacuation system for evacuating the processing chamber, and processes the substrate while concurrently supplying the processing gas through the gas supply system and executing control so as to set the pressure inside the processing chamber to a predetermined level.
The pressure inside the processing chamber is controlled while supplying the processing gas by controlling the displacement quantity achieved with the evacuation system in the related art. For instance, Japanese Laid Open Patent Publication No. H11-193464 (Reference Literature 1) discloses that the pressure inside the processing chamber is controlled at a specific level by controlling the displacement quantity with an APC unit (APC: automatic pressure controller) disposed at a piping for the evacuation system to control the degree of openness of the evacuation valve in correspondence to the pressure inside the processing chamber measured with a manometer.
However, there is a problem with the method described above in which the processing chamber internal pressure is controlled by controlling the displacement quantity of the processing chamber as described above in that if matter becomes adhered inside the evacuation pipe as the processing gas is discharged, the displacement quantity may change, the evacuation valve itself may become non-operational or accurate control of the processing chamber internal pressure may be disabled.
In addition, when the displacement quantity of the processing chamber is controlled through, for instance, APC control, the pressure control achieved through the APC control is limited to a narrow pressure control range determined by the size of the evacuation valve and the like. This leads to a problem in that each substrate processing apparatus needs to be mounted with an APC in compliance with the specifications of the particular apparatus including the processing chamber internal pressure setting selected for the substrate processing apparatus. Since the shape, the size and the like of the evacuation valve are determined in correspondence to the particular APC to be used, the evacuation system must be designed in accordance with the shape, the size and the like of the evacuation valve.
These problems are addressed in, for instance, Japanese Laid Open Patent Publication No. H08-134649 (Reference Literature 2), which discloses that the pressure inside the processing chamber is controlled in conformance to an ideal proportional curve until the pressure becomes equal to a specific pressure setting by supplying a pressure adjusting gas into the processing chamber without executing APC control.
However, Reference Literature 2 does not include any description of a specific area in the processing chamber to which the pressure adjusting gas may be supplied or any description of the processing chamber being partitioned into a space into which the processing gas is supplied and a space into which the pressure adjusting gas is supplied. Thus, as the pressure adjusting gas is supplied while the substrate processing is in progress in this apparatus, the processing gas and the pressure adjusting gas will become mixed together, altering the characteristics of the processing gas, which leads to a concern that the substrate processing may be adversely affected.